Listeriosis

Definition

Listeriosis is an infection that can occur when a person eats food that has been contaminated with bacteria called Listeria monocytogenes (L. monocytogenes).

Causes, incidence, and risk factors

The bacteriumListeria monocytogenes is found in wild animals, domesticated animals, and in soil and water. These bacteria make many animals sick, leading to miscarriage and stillbirth in domestic animals.

Vegetables, meats, and other foods you eat can get infected with the bacteria if they come in contact with contaminated soil or manure. Raw milk or products made from raw milk may carry these bacteria.

If you eat the contaminated products, you may get sick. The following people are at increased risk:

Adults over age 50

Adults with a weakened immune system

Developing fetuses

Newborns

Pregnant women

The bacteria most often cause a gastrointestinal illness. In some cases, you can develop a blood infection (septicemia) or inflammation of the covering of the brain (meningitis). Infants who are 5 days or older and children often have meningitis.

Infection in early pregnancy may cause a miscarriage. The bacteria may cross the placenta and infect the developing baby. Infections in late pregnancy may lead to stillbirth or death of the infant within a few hours of birth. About half of infants infected at or near term will die.

In adults, the disease may take many forms, depending on what organ or organ systems are infected. It may occur as: